Radio Access Techniques for Energy Effcient and Energy Harvesting based Wireless Sensor Networks
Permanent address of the item is
Summary ViewShow full item record
Traditional Wireless Sensor Networks (WSN) rely on batteries with finite stored energy. In the future with billions of such devices, it will be difficult to replace and dispose their batteries, which can cause a huge environmental threat. Hence, research is being done to eliminate batteries from sensor devices and replace them with harvesters. These harvesters can power the sensor network nodes by extracting energy from ambient sources. Harvesters are already being implemented in many real-life applications like structural health monitoring, environment monitoring and body area networks. A sensor network of multiple energy harvesting enabled devices is known as Energy Harvesting based Wireless Sensor Network (EH-WSN). For uninterrupted operation of EH-WSN, radio protocols must consider the energy harvesting constraints; (i) energy harvesting process unpredictability and; (ii) energy harvesting rate variations in time and space. EH-WSN comes with unique traits which discourage the use of existing WSNs radio protocols, as most of existing protocols are focussed on decreasing the energy consumption and increasing the network lifetime. This thesis work focusses on modifying an existing energyefficient Multipath Rings (MPR) routing protocol for low-power and low-bandwidth EH-WSN and evaluating its performance through simulations. Firstly, the topology setup phase is revised by implementing a new ring formation scheme for better data reliability. Secondly, controlled flooding of data packets is used by enabling selective forwarding, which leads to decrease in network traffic and overall energy consumption. Lastly, every node is equipped with a neighbors’ table on-board which helps in making energy-related routing decisions in multi-hop networks. A periodic energy update packet transmission helps in keeping latest neighbor information. This modified version of MPR routing protocol is called Energy Harvesting based Multipath Rings (EH-MPR) routing. This work also provides a comprehensive survey on existing MAC and Routing protocols for energy efficient and energy harvesting based WSNs. Through this work, the main constraints on using existing energy-efficient protocols for EH-WSN are discussed and depicted with the help of network simulations. The effects of using fixed duty cycle for energy harvesting enabled sensor nodes are outlined by simulating T-MAC (adaptive duty cycle) against S-MAC (fixed duty cycle). For all evaluation metrics, T-MAC outperformed S-MAC. Using Castalia’s realistic wireless channel and radio model, EH-MPR is simulated for low-power, low-data rate and low bandwidth (1 MHz) networks where satisfactory results are obtained for sub-GHz frequencies (433 MHz and 868 MHz). Next, the modified EH-MPR protocol is compared with original MPR routing under practical deployment scenarios. The metrics in consideration are successful packet transmissions, energy consumption, energy harvested-to-consumed ratio and failed packets. After thorough simulations, it was concluded that although the packet success rate is approximately equal for both protocols, EH-MPR has advantages over original MPR routing protocol in terms of energy cost and uninterrupted operations.